The Mythos Mobile Artillery is a unit that was put into use in late 2552 and was extremely rare. The Mythos uses converted covenant plasma torpedo technology and puts it into a ground side shell, which is highly mobile and packs heavy firepower. The Mythos has only a single weapon: its main cannon. The main cannon has high range and high firepower, and also has an integrated tracking system which allows it to track vehicles and aircraft. While it can attack aircraft and vehicles at long range, it requires and escort to be able to take them down at close range. It can mow down packs of infantry with ease, and due to it's four legs, stability is high and it can handle a variety of terrains.

The Mythos was only fielded in a few campaigns, and few units had access to them. The Mythos was most notably used in the Battle of Gaiden in 2552, the Coldsnap Campaign, the Battle of Toronto, and in the Arctic IV Campaign. The unit most noted for having access to the Mythos was the 359th Armored Division, which had a large quantity of them, and was part of the UNSC Army. The Mythos was often used as a troop morale booster, having the ability to raise morale, while still performing admirably as a weapon; able of taking down a scarab.